Pirfenidone is small molecule with a molecular weight of 185.23 daltons whose chemical name is 5-methyl-1-phenyl-2-(1H)-pyridone. Pirfenidone has anti-fibrotic properties and has been investigated for therapeutic benefits to patients suffering from various fibrotic conditions. It is approved in Japan for treatment of idiopathic pulmonary fibrosis (IPF) under the trade name Pirespa®, and in several European countries under the trade name Esbriet®.
Microvascular integrity and injury to the microvasculature is characterized by leakage of plasma macromolecules and can be observed even after mild ischemic insult [Dauber et al., Circ Res 66: 986-98 (1990); McDonagh et al., Circ Res 58: 127-36 (1986)]. Ischemia is the principal stimulus that induces neovascularization [Semenza, Physiology (Bethesda) 24: 97-106 (2009)]. Recent work has shown the importance of the microvasculature in the long-term survival of solid organ transplants [Jiang et al., J Clin Invest 121(6): 2336-49 (2011), incorporated by reference herein in its entirety].